National Instruments NI-9213E

The National Instruments NI 9213E is a sophisticated 16-channel thermocouple input module designed for demanding industrial automation applications. It features a 36-terminal detachable spring-terminal connector that simplifies the integration of thermocouples. With a high-performance 24-bit Delta-Sigma analog-to-digital converter (ADC), the module multiplexes and samples each channel following a differential filtering process, ensuring precise temperature measurements. The module includes two common terminals (COM) that are internally connected to an isolated ground reference, allowing for enhanced noise immunity. It is recommended to connect the COM to shielded thermocouples, with the shield linked to a common-mode voltage reference for optimal performance. For applications involving thermocouples with floating grounds, both COM and the shield should be grounded to earth.

Each channel is equipped with an open thermocouple detection (OTD) circuit to identify disconnections by utilizing a current source between the TC+ and TC- terminals. The NI 9213E also features an internal autozero channel and cold-junction compensation (CJC) to address offset error and temperature variations critically. In terms of power efficiency, the module consumes a maximum of 490 mW in active mode and only 25 μW during sleep mode, with thermal dissipation reaching up to 840 mW in active mode at 85°C.

This versatile temperature measurement module is compatible with J, K, T, E, N, B, R, and S thermocouple types, covering comprehensive NIST-defined temperature ranges. Measurement accuracy is notably high, with sensitivity in high-resolution mode reaching less than 0.02 °C for types J, K, T, E, and N, and less than 0.15 °C for types B, R, and S. In high-speed mode, sensitivities range from less than 0.25 °C for types J, K, T, and E to less than 2.8 °C for types R and S. The NI 9213E combines accuracy, flexibility, and ease of use, making it an ideal choice for precise thermal measurements in industrial settings.